Over the weekend, we had a serious power-related problem in our data center, which caused a few of our ESX servers to shut down. Fortunately, HA kicked in and brought all those VM's over to the unaffected ESX servers and started them back up. Unfortunately, it disabled the network on those VM's for some reason. Specifically, we noticed that after the VM's were started, our monitoring software was still showing them as offline. Upon investigation, we found that every VM that had been HA'd to a different host had it's network adapter disconnected (in the VM settings, when you select the network adapter, the top box saying "Connected" was unchecked). For a few VM's, that wouldn't be a huge problem, but with the 70-80 VM's that failed over this weekend, it became a huge ordeal to figure out which ones were working and which weren't...
Does anyone have any idea at all about how that checkbox was unchecked, and how to prevent that from happening in the future?